In the manufacture of multi-lamp photoflash arrays, it is common practice to employ a circuit board whereon a metallic printed circuit is attached. Frequently this printed circuit is of a material such as aluminum foil and die-stamped to a desired configuration. Moreover, the configured aluminum foil is electrically conductive and provides the electrical conductive paths necessary to the energization of a multi-lamp photoflash array.
Ordinarily, a circuit board of a material such as a glass-filled epoxy serves as a substrate and the metallic printed circuit is affixed thereto. Usually an adhesive material is applied to one surface of the printed circuit and pressure and heat are applied to the circuit and circuit board in an amount sufficient to cure the adhesive and effect attachment of the printed circuit to the circuit board.
At the present time, it is not unexpected to find circuit board material specifications which permit a board thickness variation in the range of about plus or minus ten percent. Because of such relatively great variation in board thickness, it has been found that virtually every circuit board has one or more low spots whereat contact with the adhesive covering the printed metallic circuit is not obtained. This lack of intimate contact between the adhesive-covered printed circuit and the circuit board has been found to greatly inhibit the rate of cure of the adhesive and, of course, causes a great extension of the time required for attachment between the printed circuit and the circuit board. As a result, it has become more or less standard in the laminating of photoflash arrays to compensate for this lack of intimate contact between printed circuit and circuit board by employing a large number of structures cured for a relatively long period of time, such as a minimum of about 15 minutes, for example. However, it is obvious that efficiency and economy are sacrificed when such manufacturing techniques are required.
In another aspect, the attachment of an adhesive-covered printed circuit to a circuit board utilizing a compression force tends to cause an undesired excess adhesive discharge. Thus, it is not uncommon to employ a kraft paper as a blotter to absorb this excess adhesive discharge. However, blotter material is an added cost, especially when replacement is necessary for each curing cycle, and obviously deleterious to an economical manufacturing operation.